Triconed Graphs, weighted forests, and h-vectors of matroid complexes

Abstract

A well-known conjecture of Stanley is that the h-vector of a matroid is a pure O-sequence. There have been numerous papers with partial progress on this conjecture, but it is still wide open. In particular, for graphic matroids coming from taking the spanning trees of a graph as bases, the conjecture is mostly unsolved. In graph theory, a set of vertices is called dominating if every other vertex is adjacent to some vertex inside the chosen set. Kook proved Stanley's conjecture for coned graphs, which is the class of graphs that are dominated by a single vertex. Cranford et al extended that result to biconed graphs, which is the class of graphs dominated by a single edge. In this paper we extend that result to triconed graphs, the class of graphs dominated by a path of length 2.